In-rack fire protection sprinkler system

ABSTRACT

A fire protection sprinkler system is provided for the protection of commodities including Class I-IV hazards, Group A cartoned and exposed plastics (expanded and unexpanded), flammable liquids, tires, roll paper, and aerosols, stored in a plurality of adjoining racks having a longitudinal flue space between the racks. The system includes at least one fluid supply conduit in fluid communication with a source of a fire protection fluid. The system also includes at least one solid horizontal barrier covering each rack and the longitudinal flue space at a predetermined vertical spacing. The system further includes one or more rack-level fire protection sprinklers in fluid communication with the fluid supply. The sprinklers are disposed in the vertical flue space between adjacent horizontal barriers, and each sprinkler is spaced vertically from the commodities stored between adjacent horizontal barriers.

BACKGROUND OF THE INVENTION

The following disclosure relates to a fire protection system for rack storage, and in particular to an in-rack sprinkler system capable of protecting exposed expanded and unexpanded plastics.

Rack storage is a conventional storage arrangement used in various industries and facilities. NFPA 13, Section 3.9.3.7 (2007 Ed.) states that a “rack” is “[a]ny combination of vertical, horizontal, and diagonal members that supports stored materials. Shelving in some racks can be solid, slatted, or open. Racks can also be fixed, portable, or moveable. Loading commodities can be either manual—using lift trucks, stacker cranes, or hand placement—or automatic—using machine-controlled storage and retrieval systems.” Conventionally a commodity 102 to be protected is placed on a pallet 104 and the commodity and pallet are stored together on a shelf 106 in the rack, as is shown in FIG. 1A.

Racks can be single row, double row, or multiple row, with or without solid shelving. The terms “single”, “double”, and “multiple” row refer to the depth of the rack configuration in terms of the number of pallets that can be stored back to back. For example, a double row rack 108 has a depth that can accommodate two pallets back to back as is shown in the end elevation view of the schematic shown in FIG. 1B. When the palletized commodities 102 are stored apart from one another in the racks 108, 108 the spaces formed between them can form transverse flue spaces 112, as shown in FIGS. 1A and 1C. Also, the vertical spaces between adjoining racks (i.e., between the backs of rows of storage) form what are known as longitudinal flue spaces 114 (FIGS. 1B and 1C). An isometric view of a conventional double row rack 108 showing the relationship of various parameters is shown in FIG. 2. As is shown in FIGS. 3A and 3B, double and multiple-row racks are conventionally spaced apart from other double or multiple-row racks by an aisle width 118, which is conventionally 4 or 8 feet. FIGS. 3A and 3B show, respectively, a plan view and an end elevation view of two double row rack arrangements 108 separated by an aisle having an aisle width 118.

Fire protection sprinklers conventionally are connected to a conduit to receive pressurized fire-extinguishing fluid, such as water. A typical fire protection sprinkler has a base with a threaded portion for connection to the conduit and an output orifice to output the fluid to provide fire control and/or suppression. The output orifice is sealed by a seal cap, which is held in place by a release mechanism. The release mechanism is designed to release the cap under predetermined conditions, thereby initiating the flow of fire-extinguishing fluid. A typical release mechanism includes a thermally-responsive element, e.g., a frangible bulb or fusible link, and may also include a latching mechanism.

Certain conventional fire protection sprinklers have a pair of arms that extend from the base portion and meet at a hub portion to form a frame. The hub portion is spaced apart from the output orifice of the base portion and is aligned with a longitudinal axis thereof. The hub portion may have a set-screw configured to apply a pre-tension force to the release mechanism. A deflector may be mounted on the hub, transverse to the output orifice, to provide dispersion of the output fluid.

Fire protection sprinklers may be mounted on a fluid conduit running along a ceiling and may either extend downward from the conduit, which is referred to as a “pendent” configuration, or may extend upward, which is referred to as an “upright” configuration. Alternatively, a sprinkler may be mounted on a wall, a certain distance below the ceiling, which is referred to as a “horizontal sidewall” configuration. Horizontal sidewall sprinklers have an output orifice that is oriented so that the fluid is output horizontally and sprays onto an area to be protected in front of the sprinkler.

An “extended coverage storage sprinkler (specific application),” as described in Section 55.1 of UL 199 (“Standard for Automatic Sprinklers for Fire-Protection Service,” Underwriters' Laboratories, 11th Ed., Nov. 4, 2005) is a sprinkler that is intended to be installed using the extended coverage area up to 196 square feet (e.g., 14 ft by 14 ft) and specific application criteria specified in NFPA 13 (“Standard for the Installation of Sprinkler Systems,” National Fire Protection Association, Inc., 2002 Edition). These extended coverage storage sprinklers (specific application) incorporate a heat responsive element and release mechanism that has a response time equal to or less than a standard response sprinkler used on sprinklers designed for standard spacings up to 100 square feet (e.g., 10 ft by 10 ft). Extended coverage sprinklers are installed in accordance with the NFPA 13, 8.8.2 (2007 Edition).

NFPA 13 defines a number of different types of storage sprinkler configurations and protection criteria. Commodities stored in racks are conventionally protected from fire by a fire protection system that includes sprinklers that are arranged within the storage racks, such as directly above the commodity stored on a shelf of the rack. NFPA 13, 8.13 (2007 Edition) specifies installation requirements for in-rack sprinklers and NFPA 13, 8.13.2.2 (2007 Edition) requires that in-rack sprinklers be ordinary-temperature, standard response or quick response sprinklers and have a nominal K-factor of 5.6 or 8.0.

NFPA 13, Chapter 13 describes in-rack sprinkler configuration for various classifications of commodities for storage heights up to 12 feet. According to NFPA 13.3.2 (2007 Edition), in-rack sprinklers shall have a K-factor of 5.6 or larger and operate at a minimum of 15 psi (1 bar). Table 13.2.1 and FIG. 13.2.1 of NFPA Chapter 13 (2007 Edition) specify the maximum ceiling height, maximum storage height, area of sprinkler operation, and discharge density for various hazard classes and storage types for in-rack sprinkler installations for storage up to 12 feet in height. NFPA 13, 16.2 (2007 Edition) provides “Protection Criteria for Rack Storage of Class I Through Class IV Commodities Stored Up to and Including 25 ft in Height”, Section 16.3 provides “Protection Criteria for Rack Storage of Class I Through Class IV Commodities Stored Over 25 ft in Height”, and Chapter 17 provides “Protection of Plastic and Rubber Commodities That are Stored on Racks”.

Fire protection of rack storage configuration poses a number of challenges. Fire sprinkler systems are usually required to be installed in warehouses and other similar article storage areas. Conventional sprinkler systems are generally installed in the ceiling of the building and the sprinklers spray water in the area of the fire to either control and/or extinguish the fire. However, in storage areas utilizing racks a fire which starts on a lower rack is protected from the spray emanating from the above-rack sprinkler, either by shelving above the rack or by commodities stored above the rack. This factor is significantly aggravated as the number of shelves is increased. Moreover, in cases where sprinklers are located in the ceiling above a given rack, a fire in the lower shelves of the rack may not actuate the heating-actuated sensing element of the sprinklers in sufficient time to provide an effective control of the flame. And, as noted, even when the sprinkler system is actuated the fire on the lower shelves is protected from the spray by the upper shelves, and the fire can spread upwardly.

In particular, early suppression-fast response (ESFR) sprinklers and control mode special application (CMSA) sprinklers have been used as ceiling level sprinklers in place of in-rack sprinklers. Conventional ESFR and CMSA sprinklers must operate at high pressure and discharge large volumes of water in order to provide the same level of fire protection as the in-rack sprinklers they replace. However, such increased water demand and higher operating pressure required by ESFR and CMSA sprinklers are generally undesirable consequences. Moreover, ESFR and CMSA sprinklers are not approved for the protection of all storage commodities and commodity storage configurations. Furthermore, ESFR and CMSA sprinklers are limited for use based on building heights.

It has been suggested that overhead or roof sprinkler systems be supplemented by intermediate levels of sprinklers, as for example, sprinklers mounted within the storage racks, and also within the aisle between racks (e.g., U.S. Pat. No. 3,732,930 (D'Anneo)). This arrangement was not generally satisfactory because consistent, timely, and dependable detection and sprinkler actuation was not achievable. Consequently, greater damage to stored material, and greater risk to the stored commodity and the building structure, prevented widespread use of that approach in high storage facilities. Moreover, installing sprinklers within storage racks increases the cost and complexity of the sprinkler system and reduces the flexibility of locating and relocating storage racks due to the fixed sprinkler plumbing. Also, because commodities may be routinely moved in and out of the storage racks, there is an increased risk of damage to the in-rack sprinklers from such material handling.

Also, fire protection systems using foam have been suggested for use in high-rise storage facilities. Such a system in general has a foam generator coupled with a suitable sensing system which is capable of filling the entire building volume with a light foam. Single generators capable of producing as much as 2,000 cubic feet per minute of foam are available. The time required for filling the building varies but in general ranges from 2 to 8 minutes. Such systems are not completely satisfactory since the foam may damage goods within the warehouse. Also, when the fire occurs at a high elevation the foam may not reach the height where the fire is located for some time, permitting the fire to spread to the roof or ceiling and become out-of-control. Further, the foam system mentioned in D'Anneo is relatively expensive, requires large quantities of water, and requires a great deal of maintenance, and the generators which are heavy and are normally mounted on the roof may result in structural damage if insufficient reinforcement is provided. In addition, removal of the foam from the warehouse after the fire is extinguished is a problem.

SUMMARY

As used in the remainder of this application “rack-level” denotes a position within the longitudinal flue space between rows of adjoining racks between the floor and the top of the racks, but not disposed in a rack. Moreover, as used in the remainder of this application “ceiling-level” denotes a position between the top of the racks and the ceiling of a building.

A fire protection system is provided which addresses the deficiencies of conventional in-rack and ceiling fire protection systems, and combinations of the two. In one aspect of the invention, a fire protection system is provided that uses rack-level sprinklers for fire protection for commodities stored in racks. A fire protection sprinkler system is provided for the protection of commodities including Class I-IV hazards, Group A cartoned and exposed plastics (expanded and unexpanded), flammable liquids, tires, roll paper, and aerosols, stored in a plurality of adjoining racks having a longitudinal flue space between the racks. The system includes at least one fluid supply conduit in fluid communication with a source of a fire protection fluid. The system also includes at least one solid horizontal barrier covering each rack and the longitudinal flue space at a predetermined vertical spacing. The system further includes one or more rack-level fire protection sprinklers in fluid communication with the fluid supply. The sprinklers are disposed in the vertical flue space between adjacent horizontal barriers, and each sprinkler is spaced vertically from the commodities stored between adjacent horizontal barriers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a side elevation view of a double row storage rack arrangement;

FIG. 1B shows a end elevation view of the double row storage rack arrangement shown in FIG. 1A;

FIG. 1C shows a plan view of the double row storage rack arrangement shown in FIG. 1A;

FIG. 2 shows a perspective view of another double row rack arrangement;

FIG. 3A shows a plan view of two double row rack arrangements separated by an aisle width;

FIG. 3B shows an end elevation view of the double row rack arrangements shown in FIG. 3A;

FIG. 4 shows an isometric view of an embodiment of a fire protection system in accordance with the invention; and

FIG. 5 shows an end elevation view of the system shown in FIG. 4.

FIG. 6 is an exploded view, partly in section, of the sprinkler system shown in FIG. 5.

FIG. 7 is an end elevation view of the system shown in FIG. 5 with the addition of a second level of rack storage.

FIG. 8 is an elevation view of a main array and a sprinkler system arranged in accordance with an example aspect of the invention.

FIG. 9 is a plan view of the main array and sprinkler system shown in FIG. 8 between two side arrays separated by aisles.

FIG. 10 is a plan view of the main array and sprinkler system shown in FIG. 8 with the commodities and rack structure above a horizontal barrier removed for illustration.

FIG. 11 is an elevation section view of the main array viewed along line 11-11.

FIG. 12 is a plan view of the main array and sprinkler system shown in FIG. 8 and showing an array of ceiling-level sprinklers arranged in accordance with an example aspect of the invention.

FIG. 13 includes tables showing tables of maximum temperatures of the sprinklers shown in FIG. 12 and their activation times for a test conducted.

FIGS. 14 and 15 are side elevation views of the main array shown in FIG. 8 showing damage that occurred as a result of the test conducted.

FIG. 16 is a side elevation view of the north side of a main array showing damage that occurred as a result of a test conducted on a system constructed in accordance with an example aspect of the invention.

FIG. 17 is a side elevation view of the south side of the main array shown in FIG. 16.

FIG. 18 is a side elevation view of the north side of a main array showing damage that occurred as a result of a test conducted on a system constructed in accordance with an example aspect of the invention.

FIG. 19 is a side elevation view of the south side of the main array shown in FIG. 18.

Reference numerals that are the same but which appear in different figures represent the same elements, even if those elements are not described with respect to each figure.

DETAILED DESCRIPTION

A fire protection system for single, double, and multiple row rack storage and racks for automatic rack systems is provided that includes at least one rack-level sprinkler fluidly coupled to a fluid supply conduit. In one example embodiment, the rack-level sprinkler is constructed as an extended coverage storage sprinkler. For example, in one example embodiment, the extended coverage storage sprinkler used as the rack level sprinkler is a model N252 EC fire sprinkler, manufactured by The Reliable Automatic Sprinkler Company, Inc. (Liberty, S.C.). The N252EC sprinkler has a relatively wide water distribution pattern up to 196 square feet and produces a large droplet size. The N252EC is capable of pre-wetting areas surrounding a fire that have not yet combusted so as to contain the spread of the fire to adjacent areas. In at least one embodiment where extended coverage storage sprinklers are employed as rack-level sprinklers, it is possible to eliminate using face sprinklers in the transverse flue space and to reduce the overall number of rack-level sprinklers.

As shown in FIG. 4, two racks 108 are arranged one on top of the other in two levels to form a storage array 140. Above the two levels there is placed a horizontal barrier 142. The horizontal barrier 142 can be constructed as a solid material, such as wood or metal or non-combustible material as defined in NFPA 13. Between the two levels there is placed a horizontal barrier 143, which is slatted or open or a wire grate. Rack-level sprinklers 144 are positioned below the horizontal barrier 142. The horizontal barrier 142 may be positioned at a maximum predetermined height based on the commodities 102 stored in the racks 108 and the construction of the rack-level sprinklers 144. In the example embodiment shown in FIG. 4, each rack 108 has respective heights of about 10 feet and are stacked one on top of the other in two levels forming a multi-row rack having a total height of 20 feet. It should be noted that although two racks 108 are shown stacked in the example arrangement shown in FIG. 4, the arrangement may include any number of racks 108 in combination stacked below the horizontal barrier 142 up to the predetermined height, which in the example embodiment is 20 feet.

Palletized commodities 102 are stacked in each level of the racks 108. The commodities 102 stored in the racks 108 may include one or more Class I-IV hazards, Group A cartoned and exposed plastics (expanded and unexpanded), flammable liquids, tires, roll paper, and aerosols. In the example shown in FIG. 4, in each 10-foot high level of the racks, two palletized commodities 102 are stacked on top of one another at a height that is between 8 and 9 feet tall. Thus, in the example, the horizontal barrier 142 is spaced from the commodity 102 directly below the barrier 142 by 1 to 2 feet, and the dimension from the floor to the top of the upper commodity 102 in the upper level of the racks is between 18 and 19 feet. The width of each rack 108 is about 8 feet. The rack-level sprinklers 144 are disposed in the vertical flue space 114 at a height of about 20 feet from the floor and are centered with the width of the racks 108 (i.e., at about 4 feet from the ends of the racks). The sprinklers 144 are horizontally spaced about every 8 feet in the vertical flue space 114 as shown in FIG. 4. However, in other arrangements, the rack-level sprinklers 144 may be spaced on branch line 116 at a spacing of between about 8 and 18 feet.

The horizontal barrier 142 may be made of solid metal or solid wood, such as plywood, for example. The horizontal barrier 142 may also be made from any non-combustible material as defined in NFPA 13. The horizontal barrier 142 may extend horizontally across the racks 108 and may extend fully or partially into the vertical flue space 114 above the rack-level sprinklers 144 in between the rear faces 150 of both racks 108 shown in FIGS. 5 and 7. The horizontal barrier 142 can collect heat that rises as a result of combustion occurring between the floor and the horizontal barrier 142. The horizontal barrier 142 can also direct such heat toward the thermally responsive element that activates the rack-level sprinkler 144. However, since the commodities 102 themselves, when stored in the racks 108, cover a substantial horizontal area of the rack 108, the undersides of the commodities 102 may partially substitute for dedicated horizontal barriers 142 to collect heat from below the commodities 102. For example, in one embodiment, the solid horizontal barriers 142 shown in FIGS. 5 and 7 may be substituted with one or more partial horizontal barriers to cover horizontal areas in the racks 108 that are not suitably covered by the stored commodities 102. For example, a shorter horizontal barrier (not shown) may extend from the rear face 152 of the commodity 102 and extend toward the longitudinal flue space 114. Such shorter horizontal barrier may extend into the vertical flue space 114 and may extend over the rack-level sprinklers 144.

As a substitute for solid horizontal barriers 142, either in the racks and/or in the flue spaces, horizontal barriers having one or more openings may be employed. For example, the horizontal barriers 142 may be constructed as sheets with one or more apertures.

Also, in at least one embodiment, a separate horizontal barrier (not shown) may be positioned over each rack-level sprinkler 144 in the vertical flue space 114 to collect heat around the thermally responsive element that activates the sprinkler 144. The separate horizontal barrier can be constructed of a solid material, such as one or more pieces of metal, wood, or non-combustible materials as defined in NFPA 13. The separate horizontal barrier may be a continuous piece that extends to cover a plurality of rack-level sprinklers 144 that are connected along the length of the supply conduit 116. The separate horizontal barrier may be constructed with or without openings between the horizontally adjacent sprinklers 144. Alternatively, each rack-level sprinkler 144 may be covered separately by a corresponding horizontal barrier (not shown) that covers a single sprinkler 144. Such a single-sprinkler horizontal barrier may be smaller to cover individual sprinklers 144 so that there are horizontal spaces between adjacent horizontal barriers. For structural support and positioning, the horizontal barriers may be attached to the rack-level sprinklers 144, to their supporting supply conduit piping 116, or to the racks 108.

Vertical barriers may also be used to control the spread of heat and fire horizontally within and between racks 108 and to facilitate the transmission of heat vertically toward the rack-level sprinklers 144. Such vertical barriers can compartmentalize the storage areas occupied by the commodities 102 into fire zones that are protected by rack level sprinklers 144 associated with that fire zone. The vertical barriers may be formed of solid materials such as metal and wood or non-combustible materials defined by NFPA 13. The vertical barriers may be used with or without horizontal barriers 142.

In one embodiment, horizontal and vertical barriers are not employed. When such barriers are not employed, the in-rack sprinklers 144 used are selected to have a sufficient thermal sensitivity and release timing so that the rack-level sprinklers 144 are activated.

As shown in FIG. 5, two sets of multiple-row racks 108 are arranged back-to-back with their rear faces 150 defining the longitudinal flue space 114 between the racks 108. In the example shown in FIG. 5, the rack depth (H, FIG. 2) is between 7 and 8 feet, where the depth between a front and rear face of each rack is between 3 and 4 feet and where the distance between opposing rear faces (L, FIG. 2) is about 6 to 12 inches. The rack-level sprinklers 144 are generally disposed centrally in the longitudinal flue space 114. As shown in greater detail in FIG. 6, the rack-level sprinklers 144 are approximately centered between the two sets of racks 108. For example, where the racks 108 are spaced apart by 9 inches, the sprinkler 144 is located 4.5 inches from the rear faces 150 of each rack 108. Also, as shown in FIG. 6, deflector 148 of sprinkler 144 is spaced from the top of the commodity 102 by about 7.5 inches. It should be noted however that in other embodiments, the deflector 148 may be spaced about 1 to 12 inches above the commodity 102, or greater.

In FIGS. 4 and 5 a solid horizontal barrier 142 is located above the uppermost level of the rack 108 so that up to a predetermined height of rack storage is disposed between the horizontal barrier 142 and the floor 145. A plurality of sprinklers 146 are located at the ceiling 147 above the solid horizontal barrier 142 and all of the racks 108. The ceiling sprinklers 146 provide fire protection for commodities 102 stored above the uppermost solid horizontal barrier 142, which are not protected by rack-level sprinklers 144. As discussed herein, each solid horizontal barrier 142 collects the heat between it and the solid horizontal barrier (or floor for the lowermost solid horizontal barrier 142) below it to prevent or reduce the number of the ceiling sprinklers 146 from operating in the event of a fire below the solid horizontal barrier 142. In the example embodiment described herein, the predetermined spacing between two solid horizontal barriers 142 is up to 20 feet. It will be appreciated that the floor 145 is considered a solid horizontal barrier. Such spacing between the horizontal barriers 142 may depend on the commodity 102 stored, the rack-level sprinklers 144 used, and the hazard classification, so that in other embodiments, the spacing between horizontal barriers 142 may be between about 10 to 30 feet. It should also be appreciated that in embodiments where horizontal barriers 142 are not used, the spacing between vertically adjacent sprinklers 144 may also depend on the same factors as where horizontal barriers 142 are used, i.e., on the commodity 102 stored, the rack-level sprinklers 144 used, and the hazard classification. Other factors may include the width of the aisle 118 between racks 108 and the water pressure. For example, where the hazard to be protected is less severe, a larger spacing between horizontal barriers 142 greater than 20 feet may be used, whereas in another example where the hazard is more severe, a spacing between horizontal barriers 142 less than 20 feet may be used.

The arrangement of in-rack sprinklers 142 used concurrently with ceiling sprinklers 146 in accordance with the invention described herein permits such an arrangement to be used to protect Class I-IV hazards, Group A cartoned and exposed plastics (expanded and unexpanded), flammable liquids, tires, roll paper, and aerosols stored in racks in occupancies having ceilings 147 of any height, including those having ceiling heights above 45 feet.

The ceiling-level sprinklers 146 may be any storage sprinkler having a K-factor of about 11.2 or greater. The ceiling level sprinklers 146 may also be constructed as extended coverage control mode special application (EC CMSA), special application, extended coverage (EC), storage, extended coverage storage, or early suppression fast response (ESFR) sprinklers. Also, in at least one embodiment the ceiling-level sprinklers 146 can be the same as the rack-level sprinklers 144. For example, in one embodiment of a sprinkler system, the ceiling-level sprinklers 146 and the rack-level sprinklers 144 are all model N252 EC sprinklers, manufactured by The Reliable Automatic Sprinkler Co., Inc. of Liberty, S.C. The ceiling-level sprinklers 146 are spaced from each other on a ceiling-level branch line conduit 154 at a spacing of about 8 to 20 feet. The clearance between the ceiling-level sprinklers 146 and the racks 108 and commodities 102 in the racks below the ceiling-level sprinklers 146 are determined based on the relevant agency approval listing for those ceiling-level sprinklers 146. Since sprinklers 144 below the horizontal barriers 142 (or the rack-level sprinklers 144 in cases where horizontal barriers are not used) are expected to operate in the event of a fire condition occurring below the horizontal barriers 142 (or rack-level sprinklers 144), the total hydraulic demands of the system may be reduced.

The rack-level sprinklers 144 have a K-factor that is between about 11.2 and 30. In one embodiment, all of the rack-level sprinklers 144 have the same K-factor. However, in one embodiment, not all of the rack-level sprinklers 144 have the same K-factor. For example, in one embodiment, the K-factor of the rack-level sprinklers 144 may depend on the vertical position of the sprinkler 144 in the racks 108, such that sprinklers 144 located higher in the racks have a larger K-factor than those at lower elevations, or vice versa. Alternatively, higher K-factor rack-level sprinklers 144 may be positioned in the rack 108 closer to fire zones in which more severe hazards are stored. In the case of a rack-level sprinkler 144 constructed as an N252 EC sprinkler, the rack-level sprinklers 144 operate at a minimum pressure of about 7 psig and discharge water at a rate of at least about 67 gpm. For rack-level sprinklers 144 having a smaller or larger K-factor, the sprinklers 144 will operate at a pressure of at least 7 psig. The minimum pressure is based on the commodity 102 being protected and the vertical spacing between horizontal barriers 142, or, where horizontal barriers 142 are not used, between vertically adjacent rack-level sprinklers 142.

As shown in FIGS. 5 and 7, one sprinkler line 116 extends through the vertical flue space 114 between each level of horizontal barriers 142. Each rack-level sprinkler line 116 extends between about 5 and 40 feet. The sprinkler lines 116 connected to the rack-level sprinklers 144 are separate from the line 154 connected to the ceiling-level sprinklers 146 so as to create multiple, separate fire areas. The hydraulic demand caused by the in-rack sprinklers 144 may or may not be added to the demand caused by the ceiling-level sprinklers 146.

The rack-level sprinklers 144 can be of the pendent, upright, horizontal sidewall, vertical sidewall, and conventional types (can be oriented in either a pendent or upright position). In addition, the rack-level sprinklers 144 can be constructed having ordinary, intermediate, or high sensitivity (RTI). The rack-level sprinklers 144 may be arranged with a water shield, constructed like the water shields used with model F1 and F1FR intermediate level sprinklers manufactured by The Reliable Automatic Sprinkler Company, Inc. of Liberty S.C. Also, the rack-level sprinklers 144 may be arranged with a guard, such as sprinkler guards for Model C sprinklers manufactured by The Reliable Automatic Sprinkler Company, Inc. of Liberty S.C. The rack-level sprinklers 144 may also be constructed with a thermal release element (i.e., thermally responsive element) that is a bulb or a solder element. In at least one alternate arrangement, the rack-level sprinklers 144 are not arranged in an upright orientation and/or are not constructed as upright sprinklers.

FIG. 7 shows a sprinkler system in which an upper set of racks 109 is installed above the solid horizontal barrier 142 shown in FIG. 5, below which a first level of sprinklers 144 are connected to a fluid supply conduit 116. The upper set of racks 109 and palletized commodities 102 are arranged in the same manner as the lower racks 108 and palletized commodities 102. Likewise, a second conduit 117 extends in the flue space 114 below a second solid horizontal barrier 149 at the top of the upper set of racks 108. A second level of rack-level sprinklers 144 is fluidly coupled to the second conduit 117. The second level of rack sprinklers 144 are aligned vertically and horizontally with the first level of rack-level sprinklers 144 described above with respect to FIG. 5. In the example embodiment shown in FIG. 7, the vertical spacing between the two levels of rack-level sprinklers 144 and barriers 142 and 149 is up to about 20 feet. However, in other embodiments, the vertical spacing between the two levels of rack-level sprinklers 144 and barriers 142 and 149 may be up to between about 10 to 30 feet. Though not shown in FIG. 7, additional racks may be stacked in the same way as those racks 109 of the second level and protected by providing additional rack-level sprinklers and solid horizontal barriers spaced vertically up to the predetermined limit, such as every 10 to 30 feet.

The volume between the horizontal barriers (floor 145, 142 and 149), or between vertically adjacent rack-level sprinklers 144 in arrangements without horizontal barriers, can be considered compartments. Such compartments may be further subdivided into a plurality of fire areas associated with each rack-level sprinkler 144. The hydraulic demand for the racks 108 and 109 is determined by the most demanding fire area or the most demanding ceiling sprinkler 146. Thus, as a result of the arrangement of fire areas within the racks 108 and 109 and separate ceiling sprinkler 146 arrangement, the hydraulic demand of the rack-level sprinklers 144 may or may not be added to the hydraulic demand of the ceiling level sprinklers 146.

The arrangement of rack-level sprinklers 144 and ceiling level sprinklers 146 as described herein provides a number of advantages over prior art approaches to protection for rack storage. The plurality of fire areas protected by rack-level sprinklers 144 eliminates the conventional requirements for ceiling-based sprinklers 146 to penetrate a deeply-rooted, floor-level fire. Instead, as described in accordance with an aspect of the invention, fire protection sprinklers 144 and 146 are moved closer to the origin of a fire to contain the spread of fire. Moreover, sprinklers are not required to be placed in transverse flue spaces 112 or at the faces 150 of racks, thereby improving access to the storage locations and reducing the chance of damaging the sprinklers during movement of commodities in and out of the racks. Instead, as described in accordance with an aspect of the invention, larger K-factor sprinklers capable of producing large droplet sizes, can be positioned in the vertical flue space 114 closer to the potential fire locations which can reduce the number of sprinkler heads opened during a fire and therefore reduce the amount of water typically required as compared with the ceiling-based systems.

Fire testing has been conducted for a fire protection system 800 arranged in accordance with an aspect of the invention. FIG. 8 shows a side elevation view of the tested system 800 which has a solid horizontal barrier 842 at a height of 20 feet above four levels of double row rack storage. The width of the racks 808 is about 33 feet. Above the solid horizontal barrier 842, another three levels of rack storage 809 exist such that the height from the top of uppermost commodity 802 to the floor 845 is about 35 feet and the height of the ceiling 847 above the racks is about 40 feet from the floor. Just below the horizontal barrier 842 a set of rack-level sprinklers 844 are connected to a fluid conduit 816 and are horizontally spaced from each other by about 8 feet. The horizontal barrier 842 is a solid barrier formed of ⅜ inch thick plywood.

The racks 808 and 809 are double-row racks in which are stored exposed expanded Group A plastic placed on 2-way entry, hardwood stringer pallets 804. FIG. 9 shows a plan view of the test configuration of the double-row racks 808 and 809. The racks 808 and 809 of the main array are spaced from other racks 808 and 809 by aisles that are about 8 feet wide. It should be noted that the aisle width may be about 2 feet or greater in other arrangements. As shown in FIGS. 8 and 9, an ignition source 860 is located at the base of the main array 801 approximately at the midpoint of the width of main array 801 and between two ceiling-level sprinklers 846 and 2 rack-level sprinklers 844.

Ceiling-level sprinklers 846 are fluidly connected to a conduit 854 so that the deflectors of the ceiling sprinklers 846 are spaced about 14 inches from the ceiling 847. The horizontal spacing between the ceiling-level sprinklers 846 is about 10 feet along the width of the main array 801. Ceiling-level sprinklers 146 are spaced about 10 feet on either side of the midpoint of the width of the main array 801 as shown in FIGS. 8 and 9. In the example test arrangement, the ceiling-level sprinklers 846 are ESFR pendent sprinklers having a K-factor of 16.8. The temperature rating of the ceiling sprinklers is 212 degrees Fahrenheit. The response type of the ceiling sprinklers 846 is a quick response (QR) and the thermal release element is a fusible solder link type. The nominal discharge density of the ceiling sprinklers 846 is 1.19 gpm/square foot and the nominal discharge pressure is 50 psig.

The rack-level sprinklers 844 are fluidly coupled to a 3-inch, schedule 40 branch line conduit 816 that is hydraulically separate from the conduit 854 serving the ceiling-level sprinklers 846. The rack-level sprinklers 844 are extended coverage (EC) type sprinklers oriented in a pendent configuration and having a K-factor of 25.2. The deflectors of the rack-level sprinklers 844 are spaced about 9.5 inches from the top of the commodity 802 directly below the rack-level sprinklers 844. The response type of the rack level sprinklers 844 is a quick response (QR) and the thermal release element is a fusible solder link type. The nominal discharge pressure is 30 psig and the nominal discharge flow rate is 138 gpm.

FIG. 10 shows details of the arrangement of the solid horizontal barrier 844 of the main array at the 20 foot elevation in FIG. 8, as well as solid horizontal barriers 804 and 805, respectively in arrays 802 and 803. FIG. 11 shows a section view of the main array 801 viewed from section 11-11 in FIG. 9. Rear faces 850 of rack supports 851 are spaced about 15 inches apart, while the rear faces 852 of the commodities in the racks 808 and 809 are spaced about 6 inches apart. Deflector 848 of the rack-level sprinklers 844 is approximately centered in the flue space 814 between the racks 808 and 809 and the deflector 848 is spaced about 8 inches from the uppermost side of the commodity 802. The solid horizontal plywood barrier 842 extends fully across the racks 808 and 809 and the vertical flue space 814. The conduit 816 is not disposed below the horizontal rack supports 880 of the rack frame of the racks 808 and 809. The deflector 848 of the rack-level sprinkler 844 and/or a portion of a frame of the rack-level sprinkler 844 may protrude below the rack supports 880 adjacent to the conduit 816.

FIG. 12 shows a test map of locations of an array of ceiling-level sprinklers disposed above the arrays 801, 802, and 803 where temperature measurements were taken during the testing. The test parameters and results are summarized in Table 1, below.

TABLE 1 FIRE TEST NUMBER Test 1 Test Date Aug. 8, 2012 Test Parameters Storage Type Double Row Rack Commodity Type Exposed Expanded Group A Plastic Pallet Type 2 way entry, stringer, hardwood Nominal Storage Height, ft. 35 Ceiling Height, ft. 40 Nominal Clearance, ft. 5 Aisle Width, ft. 8 Ignition Location Between 2 Ceiling and In Rack Sprinklers (Face Fire in Aisle Space) Ceiling Sprinkler System Sprinkler Type K = 16.8 ESFR Pendent Deflector to Ceiling, in. 14 Ceiling Sprinkler Spacing, 10 by 10 sprinkler by branchline ft. by ft. Temperature Rating, F. 212 Sprinkler Response Type QR (link) Nominal Sprinkler Discharge 16.8 Coefficient K, gpm/psig ^(0.5) Nominal Discharge Density, 1.19 gpm/ft² Nominal Discharge Pressure, 50 psig In Rack Sprinkler System Sprinkler Type K = 25.2 Extended Coverage Pendent Deflector to Commodity, in. 9.5 Sprinkler Spacing, ft. 8 ft. 3 in. (centered on the rack bays) Temperature Rating, F. 212 Sprinkler Response Type QR (link) Nominal Sprinkler Discharge 25.2 Coefficient K, gpm/psig ^(0.5) Nominal Discharge Pressure, 30 psig Nominal Discharge Flowrate, 138 gpm Test Results Length of Test, minutes 31 Peak Gas Temperature at 410 Ceiling Above Ignition, ° F. Maximum 1 minute Average Gas 218 Temperature at Ceiling Above Ignition, ° F. Peak Steel Temperature at 102 Ceiling Above Ignition, ° F. Maximum 1 minute Average Steel 102 Temperature at Ceiling Above Ignition, ° F. Fire Travel to Extremities No of Test Array Ceiling Sprinkler System First Sprinkler Operation 1:02 Time, min:sec Last Sprinkler Operation 1:02 Time, min:sec Number of Operated Sprinklers 1 In Rack Sprinkler System First Sprinkler Operation 0:49 (East Central Time, min:sec Sprinkler) Last Sprinkler Operation 0:52 (West Central Time, min:sec Sprinkler) Number of Operated Sprinklers 2 (out of 4 active in main array)

FIG. 13 shows maximum temperatures that were recorded during the test at the locations shown in FIG. 12 and also shows activation times of the ceiling-level sprinklers 846. The testing conducted shows that during a fire condition only two rack-level sprinklers 844 out of four rack-level sprinklers 844 operated during the fire and only one ceiling level sprinkler 846 operated. FIG. 14 shows a view of the pattern of damage to the main storage array 801 from one side and FIG. 15 shows a view of damage to the main storage array 801 from a side opposite that in FIG. 14.

Conventional in-rack sprinkler systems are designed such that in the event of a fire, up to eight sprinkler heads may operate. The sprinkler system described in accordance with the invention is constructed to reduce the number of opened sprinkler heads to five or less, which reduces the hydraulic demand on the system in the event of a fire. While the system described herein can be constructed for a new rack storage installation, it will be appreciated by those of ordinary skill in the art that the system can be implemented to retrofit existing sprinkler systems for rack storage by incorporating rack-level sprinklers into an existing rack storage sprinkler system.

Fire testing has been conducted for a fire protection system 900 arranged in accordance with an aspect of the invention. The details of the testing and the arrangement of the system are summarized in Table 2, below.

TABLE 2 Test Parameters Storage Type Double Row Rack Commodity Type Cartoned Unexpanded Group A Plastic Pallet Type 2 Way Entry, Stringer, Hardwood Horizontal Barrier Within ⅜ inch Plywood at Rack 30 ft. Elevation Nominal Storage Height, ft. 43 Ceiling Height, ft. 48 Nominal Clearance, ft. 5 Aisle Width, ft. 8 Ignition Location Between 2 Ceiling and In Rack Sprinkles (Face of Commodity in Aisle Space) Ceiling Sprinkler System Sprinkler Type K = 25.2 Extended Coverage Pendent Deflector to Ceiling, in. 14 Ceiling Sprinkler Spacing, 14 by 14 sprinkler by branchline ft. by ft. Temperature Rating, F. 212 Sprinkler Response Type QR (link) Nominal Sprinkler Discharge 25.2 Coefficient K, gpm/psig ^(0.5) Nominal Discharge Density, 0.7 gpm/ft² Nominal Discharge Pressure, 30 psig In Rack Sprinkler System Sprinkler Type K = 25.2 Extended Coverage Pendent Deflector to Bottom of 7.5 Horizontal Barrier, in. Sprinkler Spacing, ft. 8 ft. 3 in. (centered on the rack bays) Temperature Rating, F. 212 Sprinkler Response Type QR (link) Nominal Sprinkler Discharge 25.2 Coefficient K, gpm/psig ^(0.5) Nominal Discharge Pressure, 30 psig Test Results Length of Test, minutes 34 Peak Gas Temperature at 722 Ceiling Above Ignition, ° F. Maximum 1 minute Average Gas 353 Temperature at Ceiling Above Ignition, ° F. Peak Steel Temperature at 152 Ceiling Above Ignition, ° F. Maximum 1 minute Average Steel 150 Temperature at Ceiling Above Ignition, ° F. Fire Travel to Extremities No of Test Array Ignition of Target Commodity No Ceiling Sprinkler System First Sprinkler Operation 3:01 Time, min:sec Last Sprinkler Operation 3:01 Time, min:sec Number of Operated Sprinklers 1 In Rack Sprinkler System First Sprinkler Operation 2:53 (West Central Time, min:sec Sprinkler) Last Sprinkler Operation 2:59 (East Central Time, min:sec Sprinkler) Number of Operated Sprinklers 2 (out of 4 active in main array)

As distinguished from system 800, system 900 employs extended coverage fire sprinklers for ceiling sprinklers. The ceiling sprinklers used in system 900 have a nominal K-factor of 25.2 and are constructed as Model N252EC sprinkler manufactured by The Reliable Automatic Sprinkler Co., Inc., of Liberty, S.C. The rack level sprinklers used in system 900 are the same as the ceiling level sprinklers. The results of the test of system 900 are noted in Table 2.

FIG. 16 shows a photograph of the north side of the main test array protected by system 900 and the damage caused by the fire testing of system 900. FIG. 17 shows a photograph of the south side of the main test array protected by system 900 and the damage caused by the fire testing of system 900. At the aisle spacing of eight feet, no damage was observed to the commodities in either of the two racks spaced from the main array in testing system 900. Testing of system 900 confirmed that the growth of the fire was substantially vertical.

Fire testing has been conducted for a fire protection system 1000 arranged in accordance with an aspect of the invention. The details of the testing and the arrangement of the system are summarized in Table 3, below.

TABLE 3 Test Parameters Storage Type Double Row Rack Commodity Type Cartoned Unexpanded Group A Plastic (Polystyrene Cups in Corrugated Containers) Pallet Type 2 way entry, stringer, hardwood Horizontal Barrier Within ⅜ inch Plywood at Rack nominal 20 and 40 ft. Elevation Nominal Storage Height, ft. 43 Ceiling Height, ft. 48 Nominal Clearance, ft. 5 Aisle Width, ft. 4 Ignition Location Between 2 Sprinklers (offset in transverse Flue) Ceiling Sprinkler System (Initially Dry - Activated after significant fire load at the ceiling) Sprinkler Type K = 25.2 Extended Coverage Pendent Deflector to Ceiling, in. 14 Ceiling Sprinkler Spacing, 14 by 14 sprinkler by branchline ft. by ft. Temperature Rating, F. 212 Sprinkler Response Type QR (link) Nominal Sprinkler Discharge 25.2 Coefficient K, gpm/psig ^(0.5) Nominal Discharge Density, 0.7 gpm/ft² Nominal Discharge Pressure, 30 psig In Rack Sprinkler System (at nominal 20 and 40 ft. levels) Sprinkler Type K = 25.2 Extended Coverage Pendent Deflector to Commodity, in. 8 (nominal) Sprinkler Spacing, ft. 8 ft. 3 in. (centered on the rack bays) (4 sprinklers, centered on the bay of commodity) Temperature Rating, F. 165 Sprinkler Response Type QR (link) Nominal Sprinkler Discharge 25.2 Coefficient K, gpm/psig ^(0.5) Nominal Discharge Pressure, 30 (or 40 ft. elevation) psig 29 (or 20 ft. elevation) Nominal Discharge Flowrate, 138 (or 40 ft. elevation) gpm 157 (or 20 ft. elevation) Test Results Length of Test, minutes 60 Peak Gas Temperature at 1583 Ceiling Above Ignition, ° F. Maximum 1 minute Average Gas 1093 Temperature at Ceiling Above Ignition, ° F. Peak Steel Temperature at 456 Ceiling Above Ignition, ° F. Maximum 1 minute Average Steel 445 Temperature at Ceiling Above Ignition, ° F. Fire Travel to Extremities No of Test Array Ignition of Target Commodity No Ceiling Sprinkler System (Initial Operating Time without Water) - Water Began discharging at 21 minutes 1

 seconds after Ignition First Sprinkler Operation 20:40 Time, min:sec Last Sprinkler Operation 21:15 Time, min:sec Number of Operated Sprinklers 3 In Rack Sprinkler System First Sprinkler Operation 1:13 (East Central Time, min:sec Sprinkler - 20 ft. Elevation) Last Sprinkler Operation 13:40 (East Central Time, min:sec Sprinkler - 40 ft. Elevation) Number of Operated Sprinklers 5 (out of 8 active in main arrays) No operation of Target to rack Sprinklers

indicates data missing or illegible when filed

As distinguished from the testing of system 800 and system 900, system 1000 was tested in a main storage array and two other arrays having two horizontal barriers, a lower barrier at a 20 foot elevation and an upper barrier at a 40 foot elevation. Also, distinguished from testing of system 800 and system 900, in the test arrangement of system 1000, the aisle width between the main array and the other two arrays was four feet instead of eight feet, as in the test arrangement of system 800 and 900. The test arrangement used to test system 1000, employs extended coverage fire sprinklers for the ceiling and rack-level sprinklers. The ceiling and rack-level sprinklers used in system 1000 have a nominal K-factor of 25.2 and are constructed as Model N252EC sprinkler manufactured by The Reliable Automatic Sprinkler Co., Inc., of Liberty, S.C. The results of the test of system 1000 are noted in Table 2.

FIG. 18 shows a photograph of the north side of the main test array protected by system 1000 and the damage caused by the fire testing of system 1000. FIG. 19 shows a photograph of the south side of the main test array protected by system 1000 and the damage caused by the fire testing of system 1000. At the aisle spacing of four feet, no damage was observed to the commodities in either of the two racks spaced from the main array in testing system 1000. Testing of system 1000 confirmed that the growth of the fire was substantially vertical.

While the present disclosure has been described with respect to what is presently considered to be the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 

What is claimed is:
 1. A fire protection sprinkler system for the protection of commodities including Class I-IV hazards, Group A cartoned and exposed plastics (expanded and unexpanded), flammable liquids, tires, roll paper, and aerosols, stored in a plurality of adjoining racks having a longitudinal flue space between the racks, the system comprising: at least one fluid supply conduit in fluid communication with a source of a fire protection fluid; at least one solid horizontal barrier covering each rack and the longitudinal flue space at a predetermined vertical spacing; one or more rack-level fire protection sprinklers in fluid communication with the fluid supply, the sprinklers disposed in the vertical flue space between adjacent solid horizontal barriers, and wherein each sprinkler is spaced vertically from the commodities stored between adjacent solid horizontal barriers.
 2. The system according to claim 1, further including one or more ceiling-level fire protection sprinklers above an uppermost solid horizontal barrier.
 3. The system according to claim 2, wherein the ceiling-level sprinklers are extended coverage sprinklers.
 4. The system according to claim 1, wherein the predetermined vertical spacing between solid horizontal barriers is up to about 30 feet.
 5. The system according to claim 1, wherein the K-factor of the rack-level sprinklers is about 11.2 or greater.
 6. The system according to claim 5, wherein the K-factor of the rack-level sprinklers is 25.2.
 7. The system according to claim 6, wherein the fluid supply conduit delivers fluid to the at least one rack-level sprinkler at a minimum pressure of about 7 psig.
 8. The system according to claim 2, wherein the rack-level sprinklers and the ceiling-level sprinklers are the same.
 9. The system according to claim 2, wherein the building height exceeds about 30 feet and the storage rack height is up to about 5 feet of the building height, wherein one or more rack-level sprinklers are disposed at one or more predetermined heights in the longitudinal flue space of the storage rack.
 10. The system according to claim 7, wherein between each two adjacent sets of solid horizontal barriers the rack-level sprinklers are arranged horizontal in a row at a spacing of at least about 8 feet.
 11. The system according to claim 1, wherein the rack-level sprinkler is an extended-coverage sprinkler.
 12. The system according to claim 2, wherein the ceiling-level sprinkler is an extended-coverage sprinkler.
 13. The system according to claim 2, wherein the K-factor of the ceiling level sprinkler is about 11.2 or greater.
 14. The system according to claim 2, wherein the K-factor of the ceiling level sprinkler is about 25 or greater.
 15. A method of protecting commodities including Class I-IV hazards, Group A cartoned and exposed plastics (expanded and unexpanded), flammable liquids, tires, roll paper, and aerosols, stored in a plurality of adjoining racks having a longitudinal flue space between the racks, the method comprising: covering, with a solid horizontal barrier, each rack and the longitudinal flue space at a predetermined vertical spacing; and positioning one or more rack-level fire protection sprinklers in the vertical flue space below the horizontal barrier, wherein each sprinkler is spaced vertically from the commodities stored between adjacent solid horizontal barriers.
 16. The method according to claim 15, further including disposing one or more ceiling-level fire protection sprinklers above an uppermost solid horizontal barrier.
 17. The method according to claim 16, wherein the ceiling-level sprinklers are extended coverage sprinklers.
 18. The method according to claim 15, wherein the predetermined vertical spacing between horizontal barriers is up to about 30 feet.
 19. The system according to claim 1, wherein the K-factor of the rack-level sprinklers is about 11.2 or greater.
 20. A fire protection sprinkler for protecting commodities stored between two solid horizontal barriers in a plurality of adjoining racks having a longitudinal flue space between the racks, the sprinkler comprising: a body having an inlet and an outlet defining an output orifice having a K-factor of at least about 11.2, the inlet constructed to a fluid supply to dispose the body in the vertical flue space; a seal cap sealing the output orifice; a frame extending from the body; a deflector supported by the frame; and a thermally responsive element supported between the seal cap and the frame; the thermally responsive element urging the seal cap sealing the output orifice in an inactivated condition, wherein when the storage height between the solid horizontal barriers is up to about 30 feet and the sprinkler is positioned between the stored commodities and the solid horizontal barrier in the vertical flue space, the sprinkler is constructed to protect stored commodities including Class I-IV hazards, Group A cartoned and exposed plastics (expanded and unexpanded), flammable liquids, tires, roll paper, and aerosols.
 21. The system according to claim 1, wherein the conduit is not disposed below a rack support frame of the racks adjacent to the conduit.
 22. The system according to claim 1, wherein only a deflector of the rack-level sprinkler and/or a portion of a frame of the rack-level sprinkler protrude below a rack support frame of the racks adjacent to the conduit.
 23. The system according to claim 1, wherein the rack-level sprinkler is not arranged in an upright orientation and/or is not an upright sprinkler.
 24. The system according to claim 1, wherein the commodities are stored in single, double, and multiple-row racks and racks for automatic rack systems.
 25. The system according to claim 1, wherein the rack-level sprinkler is a storage sprinkler.
 26. The system according to claim 25, wherein the rack-level sprinkler is an extended coverage storage sprinkler.
 27. The system according to claim 2, wherein the ceiling sprinkler is a storage sprinkler.
 28. The system according to claim 27, wherein the ceiling sprinkler is an extended coverage storage sprinkler.
 29. The system according to claim 2, wherein the ceiling sprinkler is a special application sprinkler.
 30. The system according to claim 2, wherein the ceiling sprinkler is an early suppression fast response sprinkler.
 31. The method according to claim 16, wherein the ceiling sprinklers are storage sprinklers.
 32. The method according to claim 27, wherein the ceiling sprinklers are extended coverage storage sprinklers.
 33. The method according to claim 16, wherein the ceiling sprinklers are special application sprinklers.
 34. The method according to claim 16, wherein the ceiling sprinklers are early suppression fast response sprinklers.
 35. The method according to claim 15, wherein the rack-level sprinklers are extended coverage sprinklers.
 36. The method according to claim 15, wherein the rack-level sprinklers are storage sprinklers.
 37. The method according to claim 36, wherein the rack-level sprinklers are extended coverage storage sprinklers.
 38. The fire protection sprinkler system according to claim 1, wherein commodities are stored in another plurality of racks spaced from the plurality of racks by an aisle width, the system comprising: a fluid supply conduit associated with the another plurality of racks in fluid communication with a source of a fire protection fluid; at least one solid horizontal barrier covering each rack of the another plurality of racks at a predetermined vertical spacing; one or more rack-level fire protection sprinklers in fluid communication with the fluid supply conduit associated with the another plurality of racks, the sprinklers disposed between adjacent solid horizontal barriers, and wherein each sprinkler is spaced vertically from the commodities stored between adjacent solid horizontal barriers.
 39. The fire protection sprinkler system according to claim 38, wherein the aisle width is at least 4 feet. 